#include<iostream>
#include<string>
using namespace std;
class Quote{
public:
	Quote()=default;
	Quote(const string &book,double sales_price):bookNo(book),price(sales_price){}
	string isbn() const {return bookNo;}
	virtual double net_price(size_t n)const {return n*price;}
	virtual ~Quote()=default;
private:
	string bookNo;
protected:
	double price=0.0;
};
double print_total(ostream &os,const Quote &item,size_t n)
{
	double ret=item.net_price(n);
	os<<"ISBN: "<<item.isbn()<<" # sold: "<<n<<" total due: "<<ret<<endl;
	return ret;
}
int main()
{
	return 0;
}